| Control and Power Solutions Limited | Construction | 2023 |
| CONTROL10 Limited | Professional & scientific | 2019 |
| Controls and Machinery Services (Cardiff) Limited | Professional & scientific | 1993 |
| Convas E Services Ltd | Administrative & support | 2025 |
| Converlysis Ltd | Professional & scientific | 2020 |
| Conversant Technologies Ltd | Information & communication | 2015 |
| Conversation Makers Ltd | Information & communication | 2024 |
| CONVERT2DIGITAL Limited | Information & communication | 2014 |
| Convertmygarage Ltd | Construction | 2024 |
| Convex Recruitment Limited | Administrative & support | 2017 |
| Convexity Holdings Ltd | Financial services | 2021 |
| Convolution Ltd | Information & communication | 2017 |
| Convosight Ltd | Other services | 2025 |
| Convoy Bidco Limited | Financial services | 2024 |
| Convoy Holdings Limited | Financial services | 2024 |
| Convoy Midco 1 Limited | Financial services | 2024 |
| Convoy Midco 2 Limited | Financial services | 2024 |
| Convoy Topco Limited | Financial services | 2024 |
| Conway Court (Cardiff) Management Limited | Households | 2008 |
| Conway Marketing Limited | Administrative & support | 2017 |
| Conway Mews Management Company Limited | Households | 2014 |
| Conway Road Property Management Limited | Real estate | 2004 |
| Conwy Marina Village Management Co. Ltd. | Professional & scientific | 1985 |
| Conwy Property Developments Ltd | Construction | 2015 |
| Conybeare Heights RMC Ltd | Households | 2024 |
| Conzept Berlin-Brandenburg Ltd | Administrative & support | 2014 |
| Cooba London Ltd. | Wholesale & retail | 2017 |
| Cook & Turnbull Painting Contractors Limited | Construction | 2009 |
| Cook Film & Television Ltd | Information & communication | 2025 |
| Cook Stars Limited | Education | 2014 |
| Cooke & Arkwright Limited | Real estate | 1991 |
| Cooke & Arkwright Partnership LLP | | 2024 |
| Cooke & Partners Limited | Extraterritorial | 1991 |
| Cooked Illustrations Limited | Professional & scientific | 2020 |
| Cookes Ventures Ltd | Wholesale & retail | 2018 |
| Cookies Kreme CRE Limited | Hospitality | 2025 |
| Cooking UP Kitchens Limited | Manufacturing | 2018 |
| Cookl Limited | Wholesale & retail | 2026 |
| Cookmech Ltd | Construction | 2024 |
| Cooknock Ltd | Manufacturing | 2025 |
| Cookone Limited | Hospitality | 2015 |
| Cool BOY Household Products Co., Ltd | Wholesale & retail | 2021 |
| Cool Branding Limited | Wholesale & retail | 2021 |
| Cool Britannia Retail Limited | Wholesale & retail | 2009 |
| Cool Coastal Lets Limited | Administrative & support | 2014 |
| Cool Play (Sturminster Newton) Limited | Arts & recreation | 2004 |
| Cool Play Brands Limited | Extraterritorial | 2021 |
| Cool Side of the Pillow Ltd | Hospitality | 2025 |
| Coolcare Technical Services Limited | Construction | 2001 |
| Cooley Construction Services Ltd | Construction | 2020 |
| Coolidiots Ltd | Administrative & support | 2018 |
| Cooling Direct Limited | Other services | 2016 |
| Coolio Express Ltd | Wholesale & retail | 2025 |
| Coolnet Limited | Construction | 2019 |
| Coolsa (UK) Baby Care Products Co., Ltd | Wholesale & retail | 2019 |
| Cooltheme Limited | Real estate | 2002 |
| Coombe Gate Properties Limited | Construction | 2018 |
| Coombes Building and Landscaping Ltd | Construction | 2023 |
| Cooper Construction SW Ltd | Construction | 2026 |
| Cooper Developments Ltd | Construction | 2019 |
| Cooper Healey Coates Limited | Professional & scientific | 2014 |
| Cooper QS Ltd | Professional & scientific | 2023 |
| Cooperation Ltd | Wholesale & retail | 2024 |
| Cooperative Recruitment Ltd | Administrative & support | 2019 |
| Cooray King Holdings Limited | Professional & scientific | 2016 |
| Copa Capital | Financial services | 2018 |
| Copa Creu Limited | Information & communication | 2013 |
| Copa Gaming Ltd | Information & communication | 2023 |
| Copa Services Limited | Construction | 2018 |
| Cope Consultants Limited | Education | 2017 |
| Cope Global Logistics Ltd | Transport & logistics | 2021 |
| Cope Media Limited | Professional & scientific | 2024 |
| Cope Opticians Limited | Health & social care | 2008 |
| Copeland Digital Ltd | Information & communication | 2026 |
| Copi Development Ltd | Construction | 2019 |
| Copier Mate Limited | Wholesale & retail | 2015 |
| Copland Advertising Limited | Professional & scientific | 2019 |
| Copleston Clinic Ltd | Health & social care | 2023 |
| Coplestone Properties Limited | Real estate | 2024 |
| Copper & Co Construction Limited | Construction | 2018 |
| Copper Creek Properties Ltd | Real estate | 2023 |
| Copper Kite Developments 2.0 Limited | Construction | 2021 |
| Copper Kite Developments Limited | Extraterritorial | 2016 |
| Copper Sands Limited | Professional & scientific | 2019 |
| Copper Trail Systems Ltd | Information & communication | 2025 |
| Copperform Realisations Limited | | 1967 |
| Coppergate Property Ltd | Financial services | 2017 |
| Coppice Bedrooms Ltd | Manufacturing | 2014 |
| Coprometro Manufacture Limited | Professional & scientific | 2010 |
| Copyhaseeb Ltd | Professional & scientific | 2024 |
| Cora Berry Hotels Ltd | | 2014 |
| Coracle Pictures Ltd | Information & communication | 2017 |
| Coracle Productions Ltd | Information & communication | 2013 |
| Corala Stiftung | Administrative & support | 2019 |
| Coralbronze Limited | Financial services | 2013 |
| Coralcote Limited | Health & social care | 2017 |
| Coralcurrent Ltd | Wholesale & retail | 2025 |
| Coralkey Limited | Health & social care | 2023 |
| Coralwynn Limited | Health & social care | 2014 |
| Coram Associates Asset Ltd | Other services | 2019 |